Urban ecology of hosts and vectors of Rickettsia in a rickettsiosis-endemic city of the Yucatan peninsula, Mexico.

Rickettsioses are vector-borne zoonotic diseases that occur in urban environments. Currently, they are associated with the presence of domestic and synanthropic animals, the ectoparasites that they harbor, and their local habitat. The implementation of prevention actions relies on the understanding of the local ecology of interactions between hosts, vector species, and the etiologic agents. In this context, this study aimed to explore and describe the occurrence of infected mammals and their ectoparasites in human urban dwellings, and those characteristics of urban dwellings associated to the presence of Rickettsia infected animals in groups of households where at least one human case of rickettsiosis has occurred in the previous year of the study. Briefly, blood-samples and ectoparasites from synanthropic and domestic animals, were obtained from groups of households from different areas of an urban settlement. Serologic and molecular diagnostics helped to identify Spotted Fever Group (SFG) and TG (Typhus Group) Rickettsia in animal and ectoparasite samples. A total of 99 mammals were sampled, 29 opossums (Didelphis virginiana), 13 house mice (Mus musculus), seven black rats (Rattus rattus) and 50 dogs. Infection occurrence in opossums was 8.3% of SFG, 50% for TG, and 4.2% of undetermined group. For house mice 46.2% for SFG and 30.8% were undetermined. Black rats 28.6% of SFG and 57.1% undetermined. Finally, dogs were 19.1% of SFG, 57.4% to TG, and 23.4% belonged to undetermined group. A total of 424 ectoparasites were collected from the mammals. In opossums occurred the ticks Ambyomma sp., Ornithodoros (Alecterobius) nr. talaje, and the flea Ctenocephalides felis. In dogs we found the ticks Rhipicephalus sanguineus s. l., Amblyomma sp., O. (A.) nr. talaje, and the flea Ct. felis. No ectoparasites were collected from rodents. The occurrence of infected animals was associated primarily with the material of the backyard floor, the type of sanitary system in the household, the presence of garbage in the backyard, presence of firewood storage, stored polyethylene terephthalate (PET) containers for sale to recyclers, and the store of construction supplies in the backyard. Nonetheless a generalized linear model showed that the household with a backyard with a dirt floor or other non-concrete material has more chances of harboring infected animals (RR= 1.74, 95% CI= 1.07-2.84 and RR= 1.03, 95% CI= 0.39-2.32 respectively). In contrast, when the house has a sanitary system of urban sewer system or a latrine outside de house, the chances of having infected animals decreased significantly (RR= 0.39, 95% CI= 0.12-0.94 and RR= 0.46, 95% CI= 0.03-2.22). We conclude that both SFG and TG rickettsioses occur in animals and their ectoparasites in peridomiciles of urban households were at least one human rickettsiosis case had occurred.

Ectoparasites of Didelphis virginiana From Yucatan, Mexico.

A faunal study is presented to determine the species of ectoparasites found in the opossum Didelphis virginiana (Kerr) (Marsupialia: Didelphidae). For this, Tomahawk traps were placed in the peridomiciles of a rural town in Yucatán, to capture individuals of this marsupial and proceed to the collection of their ectoparasites. A total of 3,023 arthropods were collected from 145 opossums. The most frequent ectoparasites were the acarines Ornithodoros (Alectorobius) nr. talaje (64.8%) (Argasidae); Ornithonyssus wernecki Fonseca (53.8%) (Macronyssidae) and Didelphilicus serrifer Fain (25.5%) (Atopomelidae); the ticks Amblyomma parvum Aragão (8.3%) and A. mixtum Koch (10.3%) (Ixodidae); and the fleas Ctenocephalides felis (Bouché) (20.7%) and Pulex simulans Baker (8.3%) (Pulicidae). It is concluded that the ectoparasite fauna of this marsupial is mainly composed of euryxenous organisms, which have been documented as vectors of diseases caused by rickettsial bacteria. Since D. virginiana is widely adapted to the peridomiciliary environment in the region, this study allows recognizing those that represent a potential risk for the transmission of vector-borne zoonotic diseases.

Redescription of Periglischrus herrerai (Acari: Spinturnicidae) Associated to Desmodus rotundus (Chiroptera: Phyllostomidae: Desmodontinae), With a Description of Adult Female Heteromorphism and an Analysis of its Variability Throughout the Neotropics.

A redescription, with a discussion of new features and illustrations, for all life stages is presented for the parasitic mite Periglischrus herrerai Machado-Allison associated with the common vampire bat Desmodus rotundus (Geoffoy), including a description of the heteromorphic female and the first description of its female deutonymph. In addition, the morphological variation of P. herrerai is evaluated by morphometric analysis of the adults, concluding that there is an evident geographic variation throughout the neotropics. This study was possible by using type material of P. herrerai from the Machado-Allison collection, and voucher specimens from other collections, and specimens from an extensive surveying of hematophagous bats in some localities of the Pacific and Atlantic versants, and central Mexico.

Streblidae (Diptera: Hippoboscoidea) from Yucatan and Updated Species List for Mexico.

This study describes the diversity of ectoparasitic bat flies (Diptera: Streblidae) in the state of Yucatan, Mexico. Fieldwork was carried out from June 2010 to January 2012 in seven municipalities of Yucatan, where 13 sampling sites were selected to capture bats using mist nets. Over 156 sampling nights a total of 910 bats were captured; these belonged to 19 species in four families: Mormoopidae, Phyllostomidae, Natalidae, and Vespertilionidae. Phyllostomidae was the richest family (13 bat species), followed by Mormoopidae (3 spp.), Vespertilionidae (2 spp.), and Natalidae (1 spp.). After careful inspection of the bats, a total of 2,134 Streblid bat flies were collected, belonging to 17 species in six genera (Nycterophilia coxata Ferris, N. natali Wenzel, Trichobius diphyllae Wenzel, T. dugesii Townsend, T. galei Wenzel, T. hirsutulus Bequaert, T. intermedius Peterson and Hurka, T. parasiticus Gervais, T. uniformis Curran, T. yunkeri Wenzel, Megistopoda aranea Coquillett, M. proxima Séguy, Aspidoptera delatorrei Wenzel, Strebla alvarezi Wenzel, S. diphyllae Wenzel, S. wiedemanni Kolenati, and Metelasmus pseudopterus Coquillett). The richest and most diverse genus was Trichobius. Five species--N. natali, T. diphyllae, M. proxima, A. delatorrei, and M. pseudopterus, are new records for Yucatan, and T. galei is a new record for the country, increasing the total number of Streblidae species for Mexico to 49.